The Cisco Infrastructure group is for the discussion of technical issues that arise during the implementation, administration, or daily use of Cisco networking products such as WAN, LAN, Switching, Routing, and Network Management.

cisco interfaces configuration

My Name is Fahad I want to configure cisco router 3600 series I have 3 ethernet interfaces the first one I configured static ip address like 192.168.3.1 the second one I configured to 192.168.4.1 to 192.168.4.254 the third one i want to assign limited ip address like from 192.168.3.44 to 192.168.3.54 I need the client of this interfaces to use limited 10 ip addresses only how can I do this pls help me

In this case I think you will have to split the first subnet (192.168.3.0) in to two subnets using VLSM and create a smaller subnet of 14 IP addresses for the 3rd int and a bigger one for the 1st int. Then you could limit it to 10 IP addresses by using an ACL allowing only those 10 IPs to pass.

Your question is really confusing because you're talking about configuring an interface for certain IP Addresses and everything is assuming that you want to allow these interfaces through, but I think that you might be talking about that you want to assign DHCP addresses to the hosts on those interfaces. If that's the case, syed is the only one who answered in this regard. However, you can have the cisco 3500 switch assign those DHCP addresses or another DHCP server. If it's a 3600 series router, follow this link to help you configure it:
http://www.routergeek.net/content/view/37/38/

Most of you are thinking only about 10 IPs being permitted. Instead, as I have mentioned in my earlier post, he has to use VLSM (variable length subnetting) since he intends to use the same range of IP subnet (192.168.3.0) on two interfaces. Same time he needs to control the number of IPs to 10. On a router, you cant have the same range of IP configured on two interfaces. I think reply from Varghese also agrees to what I posted earlier.

thnks I get it what u mentioned in ur earlier post after I permit certain ip's and block the others How Can I assign my interfaces same range of Ip's For instance My first Interface has Ip address 192.168.3.1/24 and and my third interface which is required to be configured I wan to assign ip's starting from 192.168.3. 49 to 192.168.3 54 has same range of ip is that possiple
Thnks
Fahad Abdillahi Farah
IT Systems Adminstrator
Telesom Company
Hargeia Somaliland
Tell:002522-4220171

thnks Mr Varfhese T for ur post but technically If i assign my first interfaces f0/0 192.168.3.1/24 and the second /24 the third one i confured /28 subnet but there is error pls help me deeply
thnks Fahad Abdillahi

ok let me Narrate The issue I have Cisco Router 3600 series and I have two interfaces the First one is like this 193.251.33.7 subnet 255.255.255.224 the second one is like this 192.168.3.1/24 to 192.168.3.254/24 Then I want to install and add new interface in my router after that I want to assign the new and the third interface on my router same range ip address like 192.168.3.44 to 192.168.3.54 i Want to limit The number of ip address that this interface can accept to only 10 ip addresses i think it seems clear

This is a more clear narration of the situation and it is
helpful. However in normal operation of the 3600 router
it is not possible to put addresses of the same subnet
on 2 interfaces.

If there is a requirement that 2 interfaces of the 3600
share the same subnet, then you might use Integrated
Routing and Bridging. Using IRB involves configuring
bridging on both physical interfaces and configuring
a virtual interface where the IP addressing is configured.
However in this situation both interfaces would have the
same range of addresses, and part of your requirement
seems to be that one interface should have a different
range of addresses. I do not believe that this requirement
can be achieved on the 3600 router.

I have a 7206 that is connected to a T3 that goes out to an AT&T MPLS
cloud and to our remotes locations,

I have been asked to order another T3 will be used for back-up purposes
only in the event the Primary T3 goes down. The 2nd T3 will be
terminated in a 3825 with a 1 Subrate T3/E3 port.

I am having an issue with how I should do the configuration since the
2nd T3 will need to come active automatically once it sees the Primary
has gone down and then when primary is ready it will need resume the
role as primary.

I am running BGP and I do have an AS number associated with the primary
T3.

I would suggest that you think about this slightly
differently. Your description of what you need to do
seems to indicate that the second T3 should be inactive
until the primary fails and then the second T3 should
activate. That would be hard to accomplish. I would
suggest that a better approach would be to have both T3
active all the time, have both T3 run BGP. The you can
look at strategies of how to have the second T3 back up
the primary. You may think about things like prepending
the routes so that they are less attractive. But I
would suggest that you look into conditional advertising.
You can have both routers run IBGP between themselves and
have the 3825 monitor the presence of certain routes
learned by the 7206. If the learned routes are withdrawn
by the 7206 then the 3825 will advertise backup routes.

Cisco has a protocol that does exactly what you need, It is called HSRP.
I use it to automatically manage the main and backup internet connections in my company.

Basically you define the interfaces that participate in this protocol, you set the primary and secondary and define the Ip of each one and a "virtual IP". Primary assumes the virtual IP and when the primary goes down, the secondary takes that IP address, so you dont have to create any new routes.

You can find a detailed explanation in cisco website, its easy to configure and works very good. You must also be sure that your router's IOS support this protocol.

HSRP is an interesting suggestion. Unfortunately HSRP
runs only on LAN type interfaces (such as FastEthernet)
and does not run on T3 interfaces. So I do not think that
HSRP will do Mike very much good.

So what is your explanation of how the T3 interfaces send
HSRP packets to each other to negotiate which one will be
active for the point to point connection? On a LAN type
interface (such as FastEthernet) it is easy since they are
both in a directly connected subnet. But how would it work
for the T3 interfaces?

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